1. Field of the Invention
The present invention relates to a structure of a head used for a disk storage unit such as a magnetic disk storage unit, magneto-optical disk storage unit and optical disk storage unit. More particularly, the present invention relates to a head slider and a disk storage unit having a function of detecting that a head comes into contact with a disk recording medium, in which the head flies above a surface of a rotating disk recording medium with a minute distance so that information can be read from the disk recording medium and also information can be written to the disk recording medium.
2. Description of the Related Art
Magnetic disk storage units have been used as external storage units for information processors. Recently, there has been a demand for an increase in the recording density of the magnetic disk storage unit in accordance with an increase in the quantity of information to be recorded. When information is recorded in a magnetic disk storage unit at high density, it is indispensable to operate the magnetic disk storage unit in such a manner that a magnetic recording head rises a minute distance above a recording medium. Further, it is necessary that the magnetic recording head is made to slide on the recording medium under the condition that a very light load is given to the recording medium by the magnetic recording head.
In a magnetic recording head structure, as a load given to the recording medium by the magnetic recording head is very small and the size of the structure is reduced, there has been proposed a micro-contact type thin film magnetic recording head which is a thin film magnetic recording head assembling body in which a thin film magnetic recording head is combined with an elastic supporting member. In this micro-contact type thin film magnetic recording head, there are provided an electro-magnetic transducer having a medium contact surface formed by the thin film forming technique, and a long slender plate-shaped flexible supporting body having a signal lead pattern and supporting the electro-magnetic conversion element section.
This micro-contact type thin film magnetic recording head is very small, and it is difficult to make the medium contact surface of the electro-magnetic transducer come into contact with the recording medium surface in a good contacting and sliding condition. Accordingly, there is a tendency that the recording and regenerating characteristic of the thin film magnetic recording head is deteriorated. For the above reasons, there is a necessity for a micro-contact type thin film magnetic recording head which can be easily controlled in such a manner that the medium contact surface of the electro-magnetic transducer contacts with the recording medium surface in a good contacting and sliding condition.
A support mechanism for the conventional magnetic recording head includes: a slider on which the magnetic recording head is mounted; a suspension for holding the slider; a load beam for holding the suspension; and a spacer for holding the load beam. The load beam is composed of a rigid portion and an elastic portion. The elastic portion of the load beam is subjected to machining referred to as "R-bending" so that a load can be generated by the elastic portion in order to urge the slider against the recording medium. Due to the above arrangement, the slider can be urged against the recording medium with a predetermined force. When the recording medium (magnetic storage disk) is rotated in the recording and regenerating mode, the load given to the slider is counter-balanced by a rising force generated by an air flow on the slider surface. Therefore, the slider can rise above the recording medium while a minute or small gap is maintained between the slider and the recording medium.
When the recording density is increased in the conventional magnetic recording head structure described above, it is necessary to reduce the distance from the disk recording medium to the magnetic recording head slider to as small as possible. On the other hand, although the surface of the disk recording medium is smoothed by machining such as mirror surface machining, there are minute protrusions and irregularities. When the heights of these protrusions and irregularities exceed an allowable range, the magnetic recording head slider collides with the recording medium surface of the disk in the seeking operation.
In order to solve the above problems, the conventional magnetic recording head slider is provided with a detecting means for detecting contact between the magnetic recording head slider and the disk recording medium. For example, a piezo-electric element is attached onto a side of the magnetic recording head slider, and a shock caused in the contact of the magnetic recording head slider with the disk recording medium is detected by the piezo-electric element, so that the shock can be picked up in the form of an electric signal. When the contact of the magnetic recording head slider with the disk recording medium is detected in this way, an intense collision of the magnetic recording head with the disk recording medium can be avoided, and data recorded on the recording medium can be safely stored.
However, in accordance with the progress of the magnetic disk storage unit, the recording density of which is highly increased, the size of the magnetic recording head slider is reduced. Therefore, it becomes difficult to ensure a sufficiently large space to attach the piezo-electric element used for detecting contact between the magnetic recording head and the recording medium.
Japanese Examined Patent Publication No. 6-80577 discloses the following technique. An AE (acoustic emission) sensor is attached to the magnetic recording head. When an elastic wave of strain energy generated in the contact of the magnetic recording head with the disk recording medium surface is emitted in the form of a sound (ultrasonic wave), the acoustic emission sensor detects this sound. However, the following problem may be encountered in this technique. The sensitivity of the acoustic emission sensor is very high and, therefore, a sound emitted in a case other than the collision of the magnetic recording head with the recording medium surface is detected in some cases. In other words, unlike a strain sensor, it is difficult to detect only a physical shock by this acoustic emission sensor.